The traditional availability of telecommunication systems that users have come to expect and rely upon is based in part on the redundant configuration of power supplies. Redundancy provides a system with the ability to function even when, for instance, one power supply module or rectifier fails. Computer systems, including servers and workstations, are migrating toward high end availability and are incorporating redundant power capability as users become less tolerant of loss of service due to power supply failure.
Redundant power systems, also known as high availability systems or "n+1" systems, are based on the principle that a system contains at least one more rectifier than is required. If one rectifier either fails or is taken off-line, the remaining rectifiers have enough reserve capacity to meet the power requirements of the system. A single rectifier failure, therefore, will not disable the entire system. At most, it may cause the remaining rectifiers to operate at full capacity.
Current designs using "n+1" redundancy are based on an external controller that monitors each rectifier in the system. The external controllers receive information on the individual rectifier's source output current. The controller determines the number of rectifiers in the system and, using the actual source output current and the maximum available output current from each rectifier, verifies whether the current sourced by each rectifier is sufficiently below the redundancy threshold. The existence of the "n+1" redundancy condition guarantees that if one rectifier fails, the remaining rectifiers will have enough reserve capacity to meet the power consumption of the system.
The use of external controllers for determining redundancy is sound for high-end systems. With the expansion of the cost sensitive telecommunications and computer systems market, however, many customers are purchasing basic systems and expanding them as their needs require. The basic systems typically contain only a small number of rectifiers whereby each rectifier carries a significant portion of the total system load. This results in greater need for protection since without redundancy, failure of one rectifier will generally result in adverse effects on the operation of the overall system. In systems containing a large number of rectifiers, the percentage of the total load carried by each rectifier is smaller. Failure of one rectifier will have a significantly less, even negligible, impact on the system's operation. Due to the greater impact of a rectifier failure on the basic systems, cost sensitive customers who require redundancy protection are severely disadvantaged by the current method of using an external controller to determine redundancy status.
Telecommunications and computer systems are often sold with growth in mind. As business grows, the customer can expand the system processing power as necessary. Power consumption increases as more equipment is added to a system, necessitating the use of additional rectifiers. If the system contains a controller, the customer can easily determine whether he has a sufficient number of rectifiers to ensure redundancy. Some customers, however, cannot afford the added cost of a redundancy controller. Currently, a customer lacking the resources to purchase a redundant controller has two options. The customer may either estimate the number of rectifiers required, or alternatively, the customer may add more rectifiers than necessary in order to ensure redundancy. The first option does not offer a guarantee of redundancy, while the latter may result in greater cost to the customer if more rectifiers are employed than is necessary for redundancy.
What is needed in the art is a system and method for determining redundancy in a decentralized fashion, without requiring the use of an external controller.